Yan W Q, Nakamura T, Kawanabe K, Nishigochi S, Oka M, Kokubo T
Department of Orthopaedic Surgery, Faculty of Medicine, Kyoto University, Japan.
Biomaterials. 1997 Sep;18(17):1185-90. doi: 10.1016/s0142-9612(97)00057-4.
For development of thin bioactive coatings on metal implants, a dense and uniform apatite layer was coated onto titanium (Ti) implants in situ by using a new biomimetic method, which is composed of apatite nucleation and growth steps in simulated body fluid (SBF). Analysis of the coatings by thin film X-ray diffraction and scanning electron microscopy-energy dispersive X-ray microanalysis (SEM-EMPA) before implantation showed that its characteristics were very similar to those of natural bone. The coated and uncoated rectangular plates were bilaterally implanted into the tibial proximal metaphyses of rabbits. After 6, 10 and 25 weeks post-implantation, the bone bonding and bone formation at the bone-implant interfaces were evaluated by a detachment test and undecalcified histological examination. Mechanical testing in tension showed that the failure load of apatite layer-coated Ti implants was significantly higher than that of uncoated control at each time period (all P < 0.001). Histologically, it was shown that bone was deposited directly onto the apatite coating without any intervening soft tissue, while in the paired controls, interpositional soft tissue was seen at the bone-implant interface. By SEM-EPMA, a uniform calcium- and phosphorus-rich layer was detected between the coated implants and bone, but not in uncoated controls at either earlier or later time periods. The results indicate that the apatite layer deposited on Ti in situ may significantly increase the bone bonding strength by providing a bioactive surface, which allows for an early bone apposition to the implant. In addition, the apatite layer-coated Ti produced by the biomimetic process may fulfil the requirements of favourable thin coatings and strong adhesion at the metal-coating interface.
为了在金属植入物上制备薄的生物活性涂层，采用一种新的仿生方法在钛（Ti）植入物上原位涂覆致密且均匀的磷灰石层，该方法由模拟体液（SBF）中的磷灰石成核和生长步骤组成。植入前通过薄膜X射线衍射和扫描电子显微镜-能量色散X射线微分析（SEM-EMPA）对涂层进行分析，结果表明其特性与天然骨非常相似。将涂覆和未涂覆的矩形板双侧植入兔胫骨近端干骺端。植入后6、10和25周，通过脱粘试验和不脱钙组织学检查评估骨-植入物界面处的骨结合和骨形成情况。拉伸力学测试表明，在每个时间段，磷灰石层涂覆的Ti植入物的失效载荷均显著高于未涂覆的对照物（所有P<0.001）。组织学结果显示，骨直接沉积在磷灰石涂层上，没有任何中间软组织，而在配对对照物中，在骨-植入物界面处可见中间软组织。通过SEM-EPMA，在涂覆的植入物与骨之间检测到一层均匀的富含钙和磷的层，但在早期或晚期的未涂覆对照物中均未检测到。结果表明，原位沉积在Ti上的磷灰石层可通过提供生物活性表面显著提高骨结合强度，从而使骨能够早期贴附于植入物。此外，通过仿生工艺制备的磷灰石层涂覆的Ti可能满足良好的薄涂层以及金属-涂层界面处强附着力的要求。
